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Section 108 (a) of the Clean Air Act (CAA) directs the EPA administrator to identify certain pollutants that, among other things, "cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare" and to issue air quality criteria for them. These air quality criteria are to "accurately reflect the latest scientific knowledge useful in indicating the kind and extent of all identifiable effects on public health or welfare, which may be expected from the presence of [a] pollutant in the ambient air..." Under section 109 of the CAA, the EPA is then required to establish national ambient air quality standards (NAAQS) for each pollutant for which the agency has issued criteria. Section 109(d) of the CAA subsequently requires periodic review and, if appropriate, revision of existing air quality criteria to reflect advances in scientific knowledge on the effects of the pollutant on public health or welfare. The EPA is also to revise the NAAQS, if appropriate, based on the revised air quality criteria.
Ozone (O3) is one of six principal (or criteria) pollutants for which the EPA has established NAAQS. Periodically, the agency reviews the scientific basis for these standards by preparing an Integrated Science Assessment (ISA) (formerly called an Air Quality Criteria Document). The ISA, in conjunction with additional technical and policy assessments, provides the scientific basis for EPA decisions on the adequacy of the current NAAQS and the appropriateness of possible alternative standards. The Clean Air Scientific Advisory Committee (CASAC), an independent science advisory committee whose existence and whose review and advisory functions are mandated by Section 109(d)(2) of the CAA, is charged with the independent scientific review of the EPA's air quality criteria.
On Sept. 29, 2008 (73 FR 56581), the EPA formally initiated its current review of the air quality criteria for O3, requesting the submission of recent scientific information on specified topics. A draft of EPA's Integrated Review Plan for the Ozone National Ambient Air Quality Standards Review (EPA/452/P-09/001) was made available in September 2009 for public comment and was discussed by the CASAC via a publicly accessible teleconference on Nov. 13, 2009 (74 FR 54562). In August 2010, the EPA held a workshop with invited scientific experts to discuss initial draft materials prepared in the development of the ISA (75 FR 42085). The first external review draft ISA for Ozone and Related Photochemical Oxidants was released on March 4, 2011 (click here to review the document). The CASAC panel held a public meeting on May 19, 2011 to review the draft ISA (76 FR 23809). Subsequently, on Aug. 10, 2011, the CASAC panel provided a consensus review to the EPA administrator (click here to review the PDF document).
The second external review draft Integrated Science Assessment for Ozone and Related Photochemical Oxidants will be discussed at a public meeting for review by the CASAC, and public comments received will be provided to the CASAC review panel. A future Federal Register notice will inform the public of the exact date and time of that CASAC meeting.
Comments on the draft reports are due on or before Nov. 29, 2011. Click here to read the entire Federal Register notice online.